This proposal addresses the development of a rapid, inexpensive assay to screen nasopharyngeal secretions or sputum for influenza A. The assay utilizes a novel biosensor, with molecular recognition/binding as the detection element and a proprietary, integrated optic interferometer as the transducer. The unique design of the interferometer minimizes thermomechanicaI noise to provide a highly stable platform for sensing very low concentrations of specific biomolecules, chemicals or microorganisms in either aqueous or gaseous environments. The approach relies on the detection of small refractive index changes at the surface of the interferometer. When receptor molecules are immobilized on the interferometer surface, the subsequent binding of specific ligands results in a pronounced refractive index change. An assay based on this approach has a number of key advantages: l) it is rapid (equal to or less than 15 minutes), 2) it is sensitive (picogram/milliliter range), 3) it is simple (no labeling or tagging) and 4) it is low cost (< $5 unit cost, no expensive analytic instrumentation). The biosensor can be packaged as a hand-held device, suitable for out-of-lab use. Moreover, the technology offers the potential of simultaneously testing for several respiratory infections (e.g.; influenza A, influenza B, RVS, parainfluenza) in a single assay.